MC-LAG Traffic Forwarding via Pre-configured Standby ARP Ports
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Solution Overview
Problem
In dual-active systems using multi-chassis link aggregation groups (MC-LAG), the convergence time for traffic forwarding is prolonged due to the need to delete and re-learn ARP entries when a link fault occurs, causing traffic bypass and affecting system performance.
Innovation Solution
The introduction of a traffic forwarding method that sets a standby egress port for ARP entries, allowing traffic to be forwarded directly through a protection link when a fault is detected, thereby avoiding the deletion and re-learning process, and reducing convergence time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device deletes the existing ARP entry and re-learns it after a link fault, then the ARP entry can be updated to reflect the new path, but the convergence time for traffic forwarding is prolonged
Solution Approach 1:
The patent pre-configures standby egress ports in ARP entries before link faults occur. When a fault happens, the device can immediately switch to the pre-configured standby port without deleting and re-learning the ARP entry, thus reducing convergence time while maintaining ARP entry accuracy
Solution Approach 2:
The patent makes the egress port dynamic by allowing switching between main and standby ports based on link status. The ARP entry structure is enhanced to support multiple egress ports, enabling flexible adaptation to link failures without requiring full ARP entry replacement
2Reliability
If the device uses a peer-link for traffic bypass during link faults, then traffic can be forwarded through an alternative path, but the traffic bypass process increases convergence time
Solution Approach 1:
The patent pre-configures standby egress ports that point to peer-link interfaces in ARP entries before faults occur. When a link failure happens, traffic can immediately bypass through the peer-link using the pre-configured standby port, avoiding the time-consuming process of deleting and re-learning ARP entries
Data Source
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AI summary
This application provides a traffic forwarding method and a traffic forwarding apparatus. The method includes: determining, by a first network device, a first ARP entry of the access device, where the first ARP entry is used to indicate a mapping relationship among a MAC address, an IP address, and an egress port, the egress port includes a standby egress port, and the first network device is connected to the protection link through the standby egress port; receiving, by the first network device, traffic sent by a network side; determining, by the first network device, whether a fault exists in the first MC-LAG link; and when the first network device determines that a fault exists in the first MC-LAG link, sending, by the first network device, the traffic to the second network device through the protection link based on a standby egress port number in the first ARP entry, where the standby egress port number is used to indicate the standby egress port. The traffic forwarding method and the traffic forwarding apparatus in embodiments of this application help reduce a convergence time for traffic forwarding.